Fig. 3. Time spent on the open arms of the elevated plus maze. Mice with higher anxiety levels spend less time on the open arms. ( A ) Anesthesia reduced time on open arms in young mice lacking the β2subunit of the nicotinic acetylcholine receptor (β2KO), i.e. , an increase in anxiety levels ( P < 0.01). Young wild-type (WT) mice did not display any difference in anxiety levels after anesthesia. ( B ) In aged WT and β2KO mice, we failed to demonstrate any significant differences in anxiety levels between groups. Statistical significance for planned comparisons between control and anesthesia groups is indicated above the corresponding horizontal lines .Symbols within vertical bars indicate statistical significance for planned comparison with WT control. ko =β2knockout control group (young n = 18, aged n = 11); ko + sevo =β2knockout anesthesia group (young n = 8, aged n = 11); wt = wild-type control group (young n = 20, aged n = 7); wt + sevo = wild-type anesthesia group (young n = 11, aged n = 11). * P < 0.05. ** P < 0.01. - P > 0.05.